This matters for purposes of whether these communications amount to cyber-stalking or just defamation, the subject of this article in the Times.

Twitter posts have fueled defamation suits in civil courts worldwide. But this is a criminal case, invoking a somewhat rarely used law on cyberstalking. And it straddles a new, thin line between online communications that can be upsetting — even frightening — and constitutional safeguards on freedom of expression.

Federal authorities say Mr. Cassidy’s Twitter messages caused Ms. Zeoli “substantial emotional distress” and made her fear for her life, so much so that she once did not leave home for 18 months and hired armed guards to protect her residence.

In a complaint filed in federal court in Maryland, the Federal Bureau of Investigation concluded that Mr. Cassidy had published 8,000 Twitter posts, almost all of them about Ms. Zeoli and her Buddhist group, along with similar posts on several blogs.

Mr. Cassidy’s lawyers with the federal public defender’s office argue that even offensive, emotionally distressing speech is protected by the First Amendment when it is conveyed on a public platform like Twitter. Legal scholars say the case is significant because it grapples with what can be said about a person, particularly a public person like a religious leader, versus what can be said to a person.

I would love to know what Eugene Volokh thinks about this. Good thing he is interviewed:

Twitter posts have fueled defamation suits in civil courts worldwide. But this is a criminal case, invoking a somewhat rarely used law on cyberstalking. And it straddles a new, thin line between online communications that can be upsetting — even frightening — and constitutional safeguards on freedom of expression.

Federal authorities say Mr. Cassidy’s Twitter messages caused Ms. Zeoli “substantial emotional distress” and made her fear for her life, so much so that she once did not leave home for 18 months and hired armed guards to protect her residence.

In a complaint filed in federal court in Maryland, the Federal Bureau of Investigation concluded that Mr. Cassidy had published 8,000 Twitter posts, almost all of them about Ms. Zeoli and her Buddhist group, along with similar posts on several blogs.

Mr. Cassidy’s lawyers with the federal public defender’s office argue that even offensive, emotionally distressing speech is protected by the First Amendment when it is conveyed on a public platform like Twitter. Legal scholars say the case is significant because it grapples with what can be said about a person, particularly a public person like a religious leader, versus what can be said to a person.